Rapid push-to-talk call setup method and apparatus

ABSTRACT

A system ( 20 ) of establishing a rapid PTT call setup in a multi-wireless network environment, can include a first wireless network ( 24  and  26 ) such as an iDEN network optimized for rapid push-to-talk call setups in typically less than one second and a second wireless network ( 23  and  27 ) such as a CDMA wireless network operatively coupled to the first wireless network. The system can further include a communication protocol among an originating mobile subscriber unit ( 22 ), a target mobile subscriber unit ( 28 ), the first wireless network, and the second wireless network, where the first wireless network and the second wireless network receive a request for a PTT session and the PTT session is set up on the second wireless network using the first wireless network. The system can further include a PTT server ( 25 ) operatively coupled to the first wireless network and the second wireless network.

FIELD OF THE INVENTION

This invention relates generally to mobile packet data networks, andmore particularly to a method and system for rapid push-to-talk callsetup.

BACKGROUND OF THE INVENTION

In wireless communication systems mobile units or devices are requiredto operate on batteries and these mobile units will go inactive (ordormant) on the radio frequency (RF) channels after a short period ofinactivity of usage for data services, usually 30 to 60 seconds.Therefore, in push-to-talk calls using the wireless data services, boththe originating and terminating mobile units must be transitioned to theactive state (actually using RF resources) as part of the call setupprior to enabling the push-to-talk function. Once a mobile unit is inthe active state, an RF channel has been established and the mobile unitis able to transmit and/or receive data. As known in the art,push-to-talk call applications include transmission of voice andassociated signaling data, but advances in packet data networks extendpush-to-talk call applications to include images, streaming video, textmessaging, stored audio files, and other multi-media.

For typical push-to-talk call applications, the time required fortransitioning an originating mobile unit from a dormant state to theactive state can be greater than 3 seconds in current implementations.An equal or greater amount of time is required to transition theterminating mobile unit from the dormant to active state, includingadditional time to actually page the mobile device, as is known in theart. These times do not include transmission time over the air or callprocessing time required by the dispatch servers. As a result, for thepush-to-talk function total delay times experienced by the originatingmobile unit may be 10 seconds or greater.

With long call setup times, the advantages of the push-to-talk serviceas an instant communications method is diminished particularly with callsetup times of 8 seconds or even longer which can make the servicenon-viable in the marketplace. For example, users would prefer to usecellular, rather than holding down the PTT button.

A similar problem exists for group calls in the push-to-talk mode. Callsetup times may be even longer since there is a number of terminatingmobile units to connect to the originating mobile unit. Although some ofthe processing time for each of the terminating or target mobile unitsmay overlap, the total call setup time is likely to be even greater thanthe individual-to-individual call. Therefore, group calls pose an evengreater problem for the push-to-talk function in a packet data network.

Accordingly, it would be highly desirable to have a method and systemfor substantially decreasing the call setup time for private calls andgroup calls within a push-to-talk packet data network configuration.

SUMMARY OF THE INVENTION

Embodiments in accordance with the present invention can reduce apush-to-talk call setup time on a first network such as a CDMA networkby using an alternative network having a fast call setup. In the contextof a cellular network, embodiments herein can be used for a Push overCellular (PoC) system.

In a first embodiment of the present invention, a method of rapidpush-to-talk call setup in a multi-wireless network environment caninclude the step of receiving a signal at a first network and a secondnetwork requesting a push-to-talk (PTT) session or a fast paging networkconnection and setting up the push-to-talk session or the fast pagingnetwork connection on the second network using the first network. Note,the first network is optimized for rapidly establishing a push-to-talksession. The method can further include the step of relinquishingcommunication using the first network once a push-to-talk session on thesecond network is established. The PTT request can come from a mobileradio to an iDEN network serving as the first network and a CDMA networkserving as the second network. The method can further include exchangingsetup traffic between an originating mobile subscriber unit and thesecond network immediately after the originating mobile subscriber unitsends a page request or a PTT request to the first network. The methodcan also include exchanging setup traffic between a target mobilesubscriber unit and the second network immediately after the firstnetwork informs the target mobile subscriber of the page request orpush-to-talk request. Receiving setup traffic between the originatingmobile subscriber unit and the second network and between the targetmobile subscriber unit and the second network can be done substantiallyin a simultaneous manner. In other words, the second network can assigntraffic channels to an originating subscriber unit as well as to atarget subscriber unit substantially in parallel. Using the techniquesdescribed above, a group PTT call session can be established. The set upof a group PTT call session can use a fast signaling paging channel onthe first network to a target group of mobile subscriber units.

In a second embodiment of the present invention, a system ofestablishing a rapid PTT call setup in a multi-wireless networkenvironment, can include a first wireless network such as an iDENnetwork optimized for rapid push-to-talk call setups in typically lessthan one second and a second wireless network such as a CDMA wirelessnetwork operatively coupled to the first wireless network. The systemcan further include a communication protocol among an originating mobilesubscriber unit, a target mobile subscriber unit, the first wirelessnetwork, and the second wireless network, where the first wirelessnetwork and the second wireless network receive a request for a fastpaging network connection or a PTT session and the fast paging networkconnection or the PTT session is set up on the second wireless networkusing the first wireless network. The system can further include a PTTserver operatively coupled to the first wireless network and the secondwireless network.

The system can include a communication protocol that furtherrelinquishes communication using the first wireless network once apush-to-talk session on the second wireless network is established usingthe fast paging network connection. The communication protocol canfurther exchange setup traffic between the originating mobile subscriberunit and the second network immediately after the originating mobilesubscriber unit sends a page request or PTT request to the first networkand the communication protocol can also exchange setup traffic betweenthe target mobile subscriber unit and the second wireless networkimmediately after the first wireless network informs the target mobilesubscriber of the page request or PTT request. Note, the setup trafficbetween the originating mobile subscriber unit and the second wirelessnetwork and between the target mobile subscriber unit and the secondwireless network can occur substantially in a simultaneous manner. Inother words, the second wireless network assigns traffic channels to anoriginating subscriber unit and a target subscriber unit substantiallyin parallel. The communication protocol can also set up a group PTTsession using a fast signaling paging channel on the first wirelessnetwork to a target group of mobile subscriber units.

Other embodiments, when configured in accordance with the inventivearrangements disclosed herein, can include a system for performing and amachine readable storage for causing a machine to perform the variousprocesses and methods disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an existing communication protocol forsetting up a push-to-talk call session.

FIG. 2 is an illustration of timing of a CDMA2000 1× system logging twoCDMA phones with PTT capability.

FIG. 3 is an illustration of a communication protocol for setting up arapid push-to-talk call session in a multi-wireless network environmentin accordance with an embodiment of the present invention.

FIG. 4 is another illustration of a communication protocol for settingup a rapid push-to-talk call session in a multi-wireless networkenvironment in accordance with an embodiment of the present invention.

FIG. 5 is a flow chart illustrating a method of rapid push-to-talk callsetup in a multi-wireless network environment in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims defining the features ofembodiments of the invention that are regarded as novel, it is believedthat the invention will be better understood from a consideration of thefollowing description in conjunction with the figures, in which likereference numerals are carried forward.

A method and apparatus for reducing CDMA Push-To-Talk (PTT) Call Setupcan incorporate the fast call set up systems used in alternatecommunication networks. Referring to FIG. 1, a diagram for a typicalCDMA call setup is illustrated. An originating mobile subscriber unit(MS) 12 requests a PTT call or group call, and a network 14 responds bysetting up a traffic channel. The originating MS's traffic channelrequest eventually reaches a PTT server 16, which then pages the targetMSs 19 (note, a single MS is shown—in group calls other MSs in the groupare paged in parallel) using network equipment 18. The target MS 19 ispaged, responds to the page, and eventually a traffic channel isassigned using network 18. At this point, a PTT call or a group callvoice can be delivered to the target MSs (19). Note that the call setupfor the subscribers is done in a serial fashion. Much of the delay inestablishing the call is due to the serial nature of the call setup. Aswill be noted in FIGS. 2 and 3 in embodiments of the present invention,the CDMA traffic channel assignment of the subscribers can be done inparallel and the paging done at faster intervals providing significantsavings in call setup timing.

Referring to FIG. 2, timing taken in June 2005 on a CDMA2000 1× systemlogging two CDMA phones with PTT capability illustrates the following:

-   It takes greater than 3 seconds typical setup time for an    Originating mobile to get to a traffic channel (TCH).-   Paging delay: CDMA2000 paging time uses the concept of slot cycle    indexes. The paging occurs on intervals on 1.28 seconds and follows    the formula T=2ˆi. For example, for i=1 results in paging intervals    of 1.28*2ˆ1=2.56 seconds. This means a delay of up to 2.56 seconds    can occur before being received by the terminating subscriber.-   Once the mobile terminating (MT) device receives the page, it takes    ˜1.5 seconds to come onto a traffic channel. Paging delay can also    be up to 1.28 seconds depending on the slot cycle index.    From the time log in FIG. 2, the CDMA phones took 9.569 seconds from    the initial PTT until data was received on the remote phone. If the    call setup time for the terminating phone could be done in parallel    with the originating phone, approximately 2-3 seconds could be    eliminated from the setup time. This improvement would result in    approximately 30% reduction in call setup time for this example.

Referring to FIG. 3, a timing diagram for communication system 20illustrates an improvement in call setup times in accordance with anembodiment of the present invention. A first mobile subscriber (MS1) 22begins a PTT call or group call request (Origination) to a CDMA network23 as normal. In addition, a PTT call request or group call request issent to an IDEN network 24 and 26 which pages the other subscriber(s) 28in the group. (Note, simultaneous transmission of CDMA and iDENmessaging is contemplated for a dual mode CDMA/iDEN subscriber unit.

Since iDEN has a fast signaling/paging channel, the remote subscribers(28) receive the iDEN group page (or normal PTT page) quickly (typicallywithin one second). Upon receiving the group page or PTT page, theremote subscribers 28 know that a group call is being requested, andrespond accordingly. The remote subscriber(s) 28 will then initiate aCDMA session. Since the iDEN group page was delivered quickly, theremote subscribers can begin their CDMA session essentially in parallelwith the initiating unit 22 rather than waiting for the CDMA network 23and 27 to page and initiate their session. This is an improvement overthe current CDMA call setup since the initiating and target subscribers(22 and 28) were essentially operating in series, and are now operatingin parallel.

Additionally, the iDEN page delivery is significantly faster thanCDMA2000's comparable paging delivery. iDEN dispatch paging occurs at 90msec intervals, vs 2.56 sec intervals (using a Slot Cycle Index of 1).Assuming an average page delivery of ½ the interval time, iDEN's 45 msecaverage page delay is approximately 800 msec faster than CDMA's 1.28 secaverage.

Note that some infrastructure changes from current arrangements may berequired. With the proposed implementation both subscribers arerequesting resources and a PTT server 25 can be modified to accept bothrequests from the originating subscriber 22 and the target subscriber(s)28 as well as be modified to handle a PTT call or “group” callappropriately.

Referring to FIG. 4, an alternative timing diagram for a system 30reveals a virtual parallel call setup environment using a first network32 and a second network 38. The first network 32 can be optimized forfast PTT call setup such as an iDEN network or a CDMA EDVO network. Thesecond network 38 can be a conventional CDMA network. An originatingmobile subscriber (MS1) 34 can make a private call request to the firstnetwork 32 and make a corresponding PTT request to the second network38. MS1 34 can page both IDEN and CDMA infrastructure where iDENsignaling can be used to inform a target mobile subscriber (MS2) 36 ofthe CDMA PTT call to reduce call setup time. The MS2 36 can use the iDENpage to kickoff the CDMA PTT call and thus reduce setup time. The firstnetwork 32 or IDEN network at this point can continue with normaldispatch services with traffic channel (TCH) assignments for both theoriginating mobile subscriber 34 and the target mobile subscriber 36.However, in accordance with an embodiment herein, the signaling for thefirst network 32 (iDEN) is only used to initiate the CDMA call setup, sothe CDMA call setup continues without further IDEN resources since theiDEN signaling is finished. Thus, the CDMA PTT call continues on a CDMAtraffic channel where the IDEN signaling reduced the CDMA PTT call setuptime.

Referring to FIG. 5, a flow chart illustrating a method 50 of rapidpush-to-talk call setup in a multi-wireless network environment. Themethod 50 can include the step 52 of receiving a signal at a firstnetwork and a second network requesting a push-to-talk (PTT) session.Optionally, step 52 can further include the step 54 of receiving a PTTrequest from a mobile radio to an iDEN network serving as the firstnetwork and a CDMA network serving as the second network. At optionalstep 56, setup traffic can be exchanged between an originating mobilesubscriber unit and the second network immediately after the originatingmobile subscriber unit sends a PTT request to the first network. Atoptional step 58, setup traffic can be exchanged between a target mobilesubscriber unit and the second network immediately after the firstnetwork informs the target mobile subscriber of the push-to-talkrequest. The method 50 can further include the step 60 of setting up thepush-to-talk session on the second network using the first network,where the first network is optimized for rapidly establishing apush-to-talk session. At step 62 setup traffic can be received betweenthe originating mobile subscriber unit and the second network andbetween the target mobile subscriber unit and the second networksubstantially in a simultaneous manner. At step 64, the method 50 canfurther include the step of relinquishing communication using the firstnetwork once the push-to-talk session on the second network isestablished. In other words, the second network can assign trafficchannels to an originating subscriber unit as well as to a targetsubscriber unit substantially in parallel. Using the techniquesdescribed above, a group PTT call session can be established. The set upof a group PTT call session can use a fast signaling paging channel onthe first network to a target group of mobile subscriber units.

In light of the foregoing description, it should be recognized thatembodiments in accordance with the present invention can be realized inhardware, software, or a combination of hardware and software. A networkor system according to the present invention can be realized in acentralized fashion in one computer system or processor, or in adistributed fashion where different elements are spread across severalinterconnected computer systems or processors (such as a microprocessorand a DSP). Any kind of computer system, or other apparatus adapted forcarrying out the functions described herein, is suited. A typicalcombination of hardware and software could be a general purpose computersystem with a computer program that, when being loaded and executed,controls the computer system such that it carries out the functionsdescribed herein.

In light of the foregoing description, it should also be recognized thatembodiments in accordance with the present invention can be realized innumerous configurations contemplated to be within the scope and spiritof the claims. Additionally, the description above is intended by way ofexample only and is not intended to limit the present invention in anyway, except as set forth in the following claims.

1. A method of rapid push-to-talk call setup in a multi-wireless networkenvironment, comprising the steps of: receiving a signal from at least afirst network and a second network requesting a fast paging networkconnection, wherein the first network is optimized for rapidlyestablishing a push-to-talk session; and setting up the fast pagingnetwork connection on the second network using the first network.
 2. Themethod of claim 1, wherein the method further comprises the step ofrelinquishing communication using the first network once a push-to-talksession on the second network is established.
 3. The method of claim 1,wherein the step of receiving comprises the step of receiving apush-to-talk request from a mobile radio to an iDEN network serving asthe first network and a CDMA network serving as the second network. 4.The method of claim 1, wherein the method further comprises the step ofexchanging setup traffic between an originating mobile subscriber unitand the second network immediately after the originating mobilesubscriber unit sends a page request to the first network.
 5. The methodof claim 4, wherein the method further comprises the step of exchangingsetup traffic between a target mobile subscriber unit and the secondnetwork immediately after the first network informs the target mobilesubscriber of the page request.
 6. The method of claim 1, wherein themethod further comprises receiving setup traffic between an originatingmobile subscriber unit and the second network and between a targetmobile subscriber unit and the second network substantiallysimultaneously.
 7. The method of claim 1, wherein the second networkassigns traffic channels to an originating subscriber unit and a targetsubscriber unit substantially in parallel.
 8. The method of claim 1,wherein the method further comprises the step of setting up a grouppush-to-talk session using a fast signaling paging channel on the firstnetwork to a target group of mobile subscriber units.
 9. The method ofclaim 1, wherein the step of receiving comprises the step of receiving apush-to-talk request from a mobile radio to a CDMA EVDO network servingas the first network and a CDMA network serving as the second network.10. A system of establishing a rapid push-to-talk call setup in amulti-wireless network environment, comprising: a first wireless networkoptimized for rapid push-to-talk call setups in typically less than onesecond; a second wireless network operatively coupled to the firstwireless network; a communication protocol among an originating mobilesubscriber unit, a target mobile subscriber unit, the first wirelessnetwork, and the second wireless network, wherein the first wirelessnetwork and the second wireless network receive a request for a fastpaging network connection and the fast paging network connection is setup on the second wireless network using the first wireless network. 11.The system of claim 10, wherein the system further comprises apush-to-talk server operatively coupled to the first wireless networkand the second wireless network.
 12. The system of claim 10, wherein thecommunication protocol further relinquishes communication using thefirst wireless network once a push-to-talk session on the secondwireless network is established using the fast paging networkconnection.
 13. The system of claim 10, wherein the first wirelessnetwork is an iDEN network and the second wireless network is a CDMAnetwork.
 14. The system of claim 10, wherein the communication protocolfurther exchanges setup traffic between the originating mobilesubscriber unit and the second network immediately after the originatingmobile subscriber unit sends a push-to-talk or page request to the firstnetwork.
 15. The system of claim 14, wherein the communication protocolfurther exchanges setup traffic between the target mobile subscriberunit and the second wireless network immediately after the firstwireless network informs the target mobile subscriber of thepush-to-talk or page request.
 16. The system of claim 10, wherein thecommunication protocol further receives setup traffic between theoriginating mobile subscriber unit and the second wireless network andbetween the target mobile subscriber unit and the second wirelessnetwork substantially simultaneously.
 17. The system of claim 10,wherein the second wireless network assigns traffic channels to anoriginating subscriber unit and a target subscriber unit substantiallyin parallel.
 18. The system of claim 10, wherein the communicationprotocol further sets up a group push-to-talk session using a fastsignaling paging channel on the first wireless network to a target groupof mobile subscriber units.
 19. A machine-readable storage, havingstored thereon a computer program having a plurality of code sectionsexecutable by a machine for causing the machine to perform the steps of:receive a signal at a first network and a second network requesting apush-to-talk session or a fast paging network connection, wherein thefirst network is optimized for rapidly establishing a push-to-talksession; and set up the push-to-talk session or the fast paging networkconnection on the second network using the first network.
 20. Themachine readable storage of claim 18, wherein the computer programfurther comprises a plurality of code sections for causing the machineto exchange setup traffic between an originating mobile subscriber unitand the second network immediately after the originating mobilesubscriber unit sends a page request or a push-to-talk request to thefirst network.
 21. The machine readable storage of claim 19, wherein thecomputer program further comprises a plurality of code sections forcausing the machine to exchange setup traffic between a target mobilesubscriber unit and the second network immediately after the firstnetwork informs the target mobile subscriber of the page request or thepush-to-talk request.